mom is 3 times of serena
3*10=30
mom is 30
when will serena's age be half of mom's age?
serena's age in x years is 10+x
mom's age in x years is 30+x
find the value that makes this statement true
0.5(30+x)=10+x
solve
so
distribute
15+0.5x=10+x
minus 0.5x from both sides
15=10+0.5x
minus 10 from both sides
5=0.5x
times 2 both sides
10=x
in 10 years
10+10=20
when serena is 20 years old, her mom will be 40